signal-flow graph) CE Shannon. The theory and design of linear differential equation machines. Fire Control of the US National Defense Research Committee:
Gessing, R. (2004): Control fundamentals; Silesian University of Technology; ISBN 83-7335-176-0 Nyquist, H. Regeneration Theory. Bell System Tech. J. (USA:
since free variables escape to the current environment. FUNCTION acts as a closed or nonporous covering (hence the term "closure" used by Landin). Thus we